The invention relates to a process for the preparation of highly pure alkyl and arylphosphines for gas phase epitaxy processes through the reduction of alkyl and arylphosphonic acid or alkyl and arylphosphinic acid derivatives.
Highly toxic gaseous phosphine is used in the electronics industry for various applications in the area of component production primarily for the doping of silicon. It has also been increasingly used recently for the production of thin connection semiconductor layers, as well as for example, GaInAsP for optical electronic purposes. The established processes such as "metal organic vapor phase epitaxy" and, most recently, "metal organic molecular beam epitaxy" have also been used in this connection. Because of the very high risk potential due to the toxicity of the phosphine and the self ignition caused by the diphosphine which is always present as a by-product, as well as the gaseous aggregate condition at room temperature, there exists the urgent necessity of describing a source of phosphorus for doping which is less dangerous and more practical in application and preparation.
In recent times, t-butylphosphine (TBP) as an organic phosphorus hydride has been recognized as a source of phosphorus doping. The difficulty of preparing this substance for that application is the fact that it could not be synthesized to sufficient purity in view of its by-products. The long known classical methods for its synthesis create problems, not only because of the expensive production processes and the low yields, but also because of the need to use starting materials which are difficult to obtain in pure form.
It is thus the task of the invention to produce highly pure alkyl and arylphosphines for the previously stated processes which can be produced in a simple reaction process in which the alkyl and arylphosphines can easily be isolated as end products in a high yield and without problems in separation.